Large scale curvature and entropy perturbations for multiple interacting fluids

By Karim A. Malik, D. Wands, Carlo Paris, Portsmouth, Birmingham. 2002

175 citations recorded by the source corpus.

We present a gauge-invariant formalism to study the evolution of curvature perturbations in a Friedmann-Robertson-Walker universe filled by multiple interacting fluids. We resolve arbitrary perturbations into adiabatic and entropy components and derive their coupled evolution equations. We demonstrate that perturbations obeying a generalized adiabatic condition remain adiabatic in the large-scale limit, even when one includes energy transfer between fluids. As a specific application we study the recently proposed curvaton model, in which the curvaton decays into radiation. We use the coupled evolution equations to show how an initial isocurvature perturbation in the curvaton gives rise to an adiabatic curvature perturbation after the curvaton decays

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/00525aa7eed3c42f74113dda52eda10e475b4fca

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Citations in the corpus

Cosmology and Fundamental Physics with the Euclid Satellite (2012, unknown): “Perturbations are purely adiabatic when for each component α the quantity ζα ≡ −3Hδρα/ρ̇α is the same (Weinberg 2003; Malik et al. 2003).”
Observational constraints on an interacting dark energy model (2009, methodology): “C O ] 2 We consider models which are similar to simple models of reheating (Turner 1983), of dark matter decay into radiation (Cen 2001), and of curvaton decay (Malik et al. 2003) – i.e., where the interaction has the form of a decay of one species into another, with constant decay rate.”
Non-linear isocurvature perturbations and non-Gaussianities (2008, methodology): “The precise density perturbation produced after the curvaton decays can be calculated numerically [27, 28, 23], but it can also be estimated analytically using the sudden-decay approximation [6], which assumes that the curvaton decays suddenly on a spatial hypersurface of uniform total energy densit”
The growth of structure in interacting dark energy models (2009, background): “Models of the pure-decay type have been used in reheating after inflation [33], and to describe the decay of dark matter into radiation [34] or of a curvaton field into radiation [35].”